In Gram negative bacteria, production of bis-(3’,5’)-cyclic diguanylic acid (c-di-GMP) by diguanylate cyclases (DGCs) is the main trigger for production of extracellular polysaccharides (EPS) and for biofilm formation. Mutants affected in c-di-GMP biosynthesis are impaired in biofilm formation, thus making DGCs interesting targets for new antimicrobial agents with anti-biofilm activity. In this report, we describe a strategy for the screening for DGC inhibitors consisting of a combination of three microbiological assays. The primary assay utilizes an Escherichia coli strain overexpressing the adrA gene, encoding the DGC protein AdrA, and relies on detection of AdrA-dependent cellulose production as red colony phenotype on solid medium supplemented with the dye Congo red (CR). Presence of DGC inhibitors blocking AdrA activity would result in a white phenotype on CR medium.The CR assay can be performed in 96-well microtiter plates, making it suitable for high-throughput screenings. To confirm specific inhibition of c-di-GMP biosynthesis, chemical compounds positive in the CR assay are tested for their ability to inhibit biofilm formation and in a reporter gene assay which monitors expression of curli-encoding genes as a function of DGC activity. Screening of a chemical library using the described approach allowed us to identify sulfathiazole, an antimetabolite drug, as an inhibitor of c-di-GMP biosynthesis. Sulfathiazole probably affects c-di-GMP biosynthesis in an indirect fashion rather than by binding to DGCs; however, sulfathiazole represents the first example of drug able to affect biofilm formation by interfering with c-di-GMP metabolism.
Monitoring of diguanylate cyclase activity and of cyclic-di-GMP biosynthesis by whole-cell assays suitable for high-throughput screening of biofilm inhibitors / D. Antoniani, P. Bocci, A. Maciag, N. Raffaelli, P. Landini. - In: APPLIED MICROBIOLOGY AND BIOTECHNOLOGY. - ISSN 0175-7598. - 85:4(2010), pp. 1095-1104. [10.1007/s00253-009-2199-x]
Monitoring of diguanylate cyclase activity and of cyclic-di-GMP biosynthesis by whole-cell assays suitable for high-throughput screening of biofilm inhibitors
D. AntonianiPrimo
;A. Maciag;P. LandiniUltimo
2010
Abstract
In Gram negative bacteria, production of bis-(3’,5’)-cyclic diguanylic acid (c-di-GMP) by diguanylate cyclases (DGCs) is the main trigger for production of extracellular polysaccharides (EPS) and for biofilm formation. Mutants affected in c-di-GMP biosynthesis are impaired in biofilm formation, thus making DGCs interesting targets for new antimicrobial agents with anti-biofilm activity. In this report, we describe a strategy for the screening for DGC inhibitors consisting of a combination of three microbiological assays. The primary assay utilizes an Escherichia coli strain overexpressing the adrA gene, encoding the DGC protein AdrA, and relies on detection of AdrA-dependent cellulose production as red colony phenotype on solid medium supplemented with the dye Congo red (CR). Presence of DGC inhibitors blocking AdrA activity would result in a white phenotype on CR medium.The CR assay can be performed in 96-well microtiter plates, making it suitable for high-throughput screenings. To confirm specific inhibition of c-di-GMP biosynthesis, chemical compounds positive in the CR assay are tested for their ability to inhibit biofilm formation and in a reporter gene assay which monitors expression of curli-encoding genes as a function of DGC activity. Screening of a chemical library using the described approach allowed us to identify sulfathiazole, an antimetabolite drug, as an inhibitor of c-di-GMP biosynthesis. Sulfathiazole probably affects c-di-GMP biosynthesis in an indirect fashion rather than by binding to DGCs; however, sulfathiazole represents the first example of drug able to affect biofilm formation by interfering with c-di-GMP metabolism.Pubblicazioni consigliate
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